Systems and Methods for Server Failover and Load Balancing

ABSTRACT

Systems and methods for server failover and/or load balancing are provided herein. Systems for server failover and load balancing may include a computer system in electronic communication over a network with one or more client applications, the computer system including a plurality of servers, and an engine stored on and executed by a client, the engine configured to allow one or more clients to select a target server among the plurality of servers using a client application identifier.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 62/179,969 filed May 26, 2015, whichis incorporated herein by reference in its entirety and made a parthereof.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to systems, methods and/ormedia for use in server failover and/or load balancing. Morespecifically, the present disclosure relates to systems, methods and/ormedia for use in server failover and/or load balancing using clients.

BACKGROUND INFORMATION

Backend servers that provide services to clients need to be available atall times. When a particular server fails, a mechanism needs to be inplace to route clients to one or more alternate servers. For example,Web services typically utilize a front-end load balancer or router,which sends requests to functioning servers. While fast, the loadbalancer or router is itself a critical single point of failure andintroduces additional costs. Alternatively, a new server could beinstantiated and the DNS (domain name system) entry for the servicecould be changed to point to the new server. However, there aresignificant delays in propagating new DNS entries.

SUMMARY OF THE INVENTION

In the mechanisms described, the routing of requests and changing ofpointers is performed on the backend side (e.g., on the serversthemselves) without client involvement.

It has been determined that it is possible to involve and/or otherwiseutilize clients in server failover and/or load balancing.

In some embodiments, a system (and/or method and/or medium) may provideload balancing, server failover, scaling, data localization and/orredundancy. The system (and/or method and/or medium) may achieve loadbalancing by uniformly selecting a target server over all servers basedon a random client application identifier (CAI). The system (and/ormethod and/or medium) may provide failover by selecting appropriatealternate servers. The system (and/or method and/or medium) may achievescalability by extending system capacity by adding new servers andinforming directory services about the new additions. The system (and/ormethod and/or medium) may provide data localization and redundancy bylimiting data replication to the first N servers on the CAI-specificHighest Random Weight (HRW) sorted list. The system (and/or methodand/or medium) may provide the above features so when two or moreclients agree on the same CAI, they will always select the same serveror the same subset of servers. The system (and/or method and/or medium)may provide these benefits without any centralized services,bottlenecks, and/or single points of failure on the server side. Thereis no need for load balancers, third party directory involvement (e.g.,DNS), or system-wide data replication.

In some embodiments, a system comprises an engine executed by one ormore clients to select a target server or server subset among aplurality of servers, using a client application identifier. In someembodiments, two or more clients, using the same client applicationidentifier, select the same target server or server subset. In someembodiments, each of the plurality of servers is coupled to the one ormore clients and configured to provide one or more service classes, theservices classes including application services and directory services.In some embodiments, the application services on each server serve onlya subset of all client applications. In some embodiments, the directoryservices of each server are configured to provide a list of servers,each server tagged with the application services that server supports.In some embodiments, the engine includes a service mapping subsystemconfigured to map each client application identifier to the targetserver or server subset. In some embodiments, the service mappingsubsystem is configured to map said client application identifier usingHighest Random Weight. In some embodiments, the client applicationidentifier comprises a large number. In some embodiments, the engine isexecuted by a first one of the one or more clients to select a targetserver or server subset among the plurality of servers using the clientapplication identifier; and the engine is executed by a second one ofthe one or more clients to select the same target server or serversubset among the plurality of servers using the client applicationidentifier. In some embodiments, the client application identifier is alarge number. In some embodiments, the large number comprises at least128 bits. In some embodiments, the large number comprises at least 512bits.

In some embodiments, the system comprises a computer system that is inelectronic communication over a network (or otherwise coupled (via anytype(s) of communication link(s))) with one or more clients, thecomputer system including a plurality of servers, and an engine storedon and/or executed by the one or more clients, the engine configured topermit the one or more client applications to select a target serveramong the plurality of servers using a client application identifier. Insome embodiments, the client application identifier is a large number.In some embodiments, the large number comprises at least 128 bits. Insome embodiments, the large number comprises at least 512 bits.

In some embodiments, a method comprises electronically (or otherwise)receiving a directory list with server identities for a plurality ofservers, electronically (or otherwise) receiving an application specificdirectory list using a client application identifier to identify serverswith a desired application, applying, by an engine stored on and/orexecuted by a client, a Highest Random Weight to the applicationspecific directory list to electronically (or otherwise) generate aclient application identifier specific sorted list of servers thatprovide the desired application, and attempting by the client toelectronically (or otherwise) contact a server from the clientapplication identifier specific sorted list of servers by starting atthe top and working down the list. In some embodiments, the clientapplication identifier is a large number. In some embodiments, thesorted list may comprise any type(s) of information, in any form(s),that defines an order in which to attempt to contact servers until atleast one functioning one of the servers is contacted. In someembodiments, the large number comprises at least 128 bits. In someembodiments, the large number comprises at least 512 bits.

In some embodiments, a method comprises: executing, by one or moreclients, an engine to select a target server or server subset among aplurality of servers, using a client application identifier. In someembodiments, two or more clients, using the same client applicationidentifier, select the same target server or server subset. In someembodiments, each of the plurality of servers is coupled to the one ormore clients and configured to provide one or more service classes, theservices classes including application services and directory services.In some embodiments, the application services on each server serve onlya subset of all client applications. In some embodiments, the directoryservices of each server are configured to provide a list of servers,each server tagged with the application services that server supports.In some embodiments, the engine includes a service mapping subsystemconfigured to map each client application identifier to the targetserver or server subset. In some embodiments, the service mappingsubsystem is configured to map said client application identifier usingHighest Random Weight. In some embodiments, the client applicationidentifier comprises a large number. In some embodiments, executing anengine to select a target server or server subset among a plurality ofservers, using a client application identifier comprises: executing, bya first one of the one or more clients, an engine to select a targetserver or server subset among a plurality of servers, using a clientapplication identifier; and executing, by a second one of the one ormore clients, the engine to select the target server or server subsetamong the plurality of servers, using the client application identifier.In some embodiments, executing an engine to select a target server orserver subset among a plurality of servers, using a client applicationidentifier comprises: receiving, by an engine executed by a client,information indicative of identifies of servers that provide a desiredapplication; and generating, by the engine executed by the client, basedat least in part on the information and a client application identifier,a client application identifier specific sorted list of servers thatprovide the desired application. In some embodiments, the sorted listmay comprise any type(s) of information, in any form(s), that defines anorder in which to attempt to contact servers until at least onefunctioning one of the servers is contacted. In some embodiments, thelarge number comprises at least 128 bits. In some embodiments, the largenumber comprises at least 512 bits.

In some embodiments, a non-transitory computer-readable medium hascomputer-readable instructions stored thereon that, if executed by acomputer system, result in a method comprising: executing, by one ormore clients, an engine to select a target server or server subset amonga plurality of servers, using a client application identifier. In someembodiments, two or more clients, using the same client applicationidentifier, select the same target server or server subset. In someembodiments, each of the plurality of servers is coupled to the one ormore clients and configured to provide one or more service classes, theservices classes including application services and directory services.In some embodiments, the application services on each server serve onlya subset of all client applications. In some embodiments, the directoryservices of each server are configured to provide a list of servers,each server tagged with the application services that server supports.In some embodiments, the engine includes a service mapping subsystemconfigured to map each client application identifier to the targetserver or server subset. In some embodiments, the service mappingsubsystem is configured to map said client application identifier usingHighest Random Weight. In some embodiments, the client applicationidentifier comprises a large number. In some embodiments, executing anengine to select a target server or server subset among a plurality ofservers, using a client application identifier comprises: executing, bya first one of the one or more clients, an engine to select a targetserver or server subset among a plurality of servers, using a clientapplication identifier; and executing, by a second one of the one ormore clients, the engine to select the target server or server subsetamong the plurality of servers, using the client application identifier.In some embodiments, executing an engine to select a target server orserver subset among a plurality of servers, using a client applicationidentifier comprises: receiving, by an engine executed by a client,information indicative of identifies of servers that provide a desiredapplication; and generating, by the engine executed by the client, basedat least in part on the information and a client application identifier,a client application identifier specific sorted list of servers thatprovide the desired application. In some embodiments, the sorted listmay comprise any type(s) of information, in any form(s), that defines anorder in which to attempt to contact servers until at least onefunctioning one of the servers is contacted. In some embodiments, thelarge number comprises at least 128 bits. In some embodiments, the largenumber comprises at least 512 bits.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the disclosure will be apparent from thefollowing Detailed Description, taken in connection with theaccompanying drawings, in which:

FIG. 1 is a diagram showing a server failover and load balancing system,in accordance with some embodiments;

FIG. 2 is a diagram illustrating subsystems of a failover and loadbalancing engine, in accordance with some embodiments;

FIG. 3 is a diagram illustrating a client communicating with a server,in accordance with some embodiments;

FIG. 4 is a flowchart of a process, in accordance with some embodiments;

FIG. 5 is a diagram showing an architecture, in accordance with someembodiments;

FIG. 6 is a graphical representation of a list (or other definition), inaccordance with some embodiments;

FIG. 7 is a graphical representation of a list (or other definition), inaccordance with some embodiments;

FIG. 8 is a graphical representation of a list (or other definition), inaccordance with some embodiments;

FIG. 9 is a graphical representation of a list (or other definition)prior to sorting after hashing, in accordance with some embodiments;

FIG. 10 is a graphical representation of a list (or other definition),in accordance with some embodiments;

FIG. 11 is a graphical representation of a list (or other definition)prior to sorting after hashing, in accordance with some embodiments;

FIG. 12 is a graphical representation of a list (or other definition),in accordance with some embodiments; and

FIG. 13 is a flowchart of a process, in accordance with someembodiments.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present disclosure relates generally to systems and methods forserver failover and/or load balancing. More specifically, the presentdisclosure utilizes clients, which are more numerous than servers, toaddress server failover and/or load balancing and/or other tasks.Accordingly, the server system is simplified as the server system is notresponsible for providing uninterrupted service to clients. Instead,each client is in charge of finding a functioning server. At the sametime, the server selection method guarantees that client-specificinformation will be available on the server chosen.

FIG. 1 is a diagram showing a server failover and load balancing system10, in accordance with some embodiments.

Referring to FIG. 1, in accordance with some embodiments, the serverfailover and load balancing system 10 comprises a plurality of servers12 (e.g., servers 12 a-12 n) and one or more clients 22 (e.g., clients26 a-26 c). Each of the one or more clients 22 (e.g., clients 26 a-26 c)may include a server failover and load balancing engine (e.g., serverfailover and load balancing engines 16 a-16 c, respectively). Each ofthe plurality of servers 12 may comprise any suitable type(s) ofcomputer servers (e.g., a server with an INTEL microprocessor, multipleprocessors, multiple processing cores, etc.) running any suitableoperating system (e.g., Windows by Microsoft, Linux, etc.). One or moreof the plurality of servers 12 (e.g., servers 12 a-12 n) may include adatabase (e.g., databases 14 a-14 n, respectively) stored therein oroperatively connected thereto. Each database may be stored on itsserver, or located externally therefrom (e.g., in a separate databaseserver in communication with the server failover and load balancingsystem 10). As further described below, one or more of the plurality ofservers 12 may also include a server failover and load balancing engine(not shown) that may be the same as and/or similar to the serverfailover and load balancing engines 16 a-16 c. Each of the plurality ofservers 12 is remotely accessible such that it can communicate, througha network 20 (and/or via any other type(s) of communication link(s)),with one or more of the one or more clients 22. Each of the one or moreclients 22 may include any type(s) of client device (e.g., a personalcomputer system 26 a, a smart cellular telephone 26 b, a tablet computer26 c, and/or other electronic devices). Network communication may beover the Internet using standard TCP/IP communications protocols (e.g.,hypertext transfer protocol (HTTP), secure HTTP (HTTPS), file transferprotocol (FTP), electronic data interchange (EDI), etc.), through aprivate network connection (e.g., wide-area network (WAN) connection,emails, electronic data interchange (EDI) messages, extensible markuplanguage (XML) messages, file transfer protocol (FTP) file transfers,etc.), or any other suitable wired or wireless electronic (or otherwise)communications format and system as should be understood by those ofordinary skill in the art.

As can be seen, the system 10 is a distributed system, which removes anysingle point of failure.

In accordance with some embodiments, the system 10 provides services intwo basic service classes: directory services and application services.Each of the plurality of servers 12 (sometimes referred to herein asnodes) in the system 10 can provide services in one or both of suchservice classes (i.e., directory services and application services). Insome embodiments, the application services include real timecommunication services (e.g., a real time communication session betweentwo or more clients) and/or storage services (e.g., use of read/writestorage by one or more clients).

In some embodiments, all directory services on all nodes contain serviceinformation about the entire system. In contrast thereto, applicationservices (e.g., used by the client application identifier subsystem 30)on particular nodes only serve a fraction of all clients, so there is noneed to distribute information about all clients to all applicationnodes. This reduces negative impact on system efficiency. Localizationof client information on a subset of servers greatly improves networkand storage performance, and enables linear capacity scaling (e.g., justby adding servers to the system).

The directory service (e.g., information directory service) provides alist of known servers, where each server is tagged or associated withall the application services it supports. In some embodiments, this listmay be generated as follows as servers become “on-line” and/or otherwiseavailable. Initially, a first server becomes “on-line” and/or otherwiseavailable. A second server thereafter becomes “on-line” and/or otherwiseavailable and is given the IP address of the first server. The secondserver subsequently sends a request to the first server for a list (orother definition) of all servers that are in the system 10 and known tothe first server. After receiving a response from the first server, thesecond server sends a request to each additional server on the list (orother definition) for a list (or other definition) of all servers thatare in the system 10 and known to such additional server. The list fromthe first server may initially consist of only the first server. Thus,the second server may not send any additional requests. However, theprocess may be repeated as each additional server becomes “on-line”and/or otherwise available and thus each additional server obtains alist (or other definition) of at least some of the servers in the system10. Each server may also broadcast a list (or other definition) ofservers known to such server, in which case, each server in the systemwill eventually have a list (or other definition) of each server in thesystem 10. In some embodiments, the list (or other definition) may alsoindicate the capabilities (e.g., application services) of each server onthe list.

The directory services of a server may be used by one or more clientcomputer systems to obtain a list (or other definition) of the serversthat are in the system 10 and available to the one or more clientcomputer systems. In some embodiments, a client may send a request to aserver for such a list (or other definition). The client may thereafterreceive a response with the list (or other definition) of servers thatare in the system 10 and available to such client. In some embodiments,the client may send the request to any server in the system 10. In someother embodiments, the client may be required to send the request to oneor more designated servers (e.g., a centralized directory service).Clients may occasionally refresh this information by querying directoryservers (e.g., in real time, every few hours or days, etc.).

FIG. 6 is a graphical representation of a list (or other definition)that may be received by one of the one or more clients 22, in accordancewith some embodiments.

Referring to FIG. 6, the list (or other definition), which is shown inthe form of a table 600 having a plurality of entries, e.g., entries602-628, indicating all of the servers 12 that are in the system 10 andavailable to the client that requested the list. In the illustratedembodiment, each entry is associated with a particular one of theplurality of servers 12 available to the client, and indicates: (i) anIP address or other identifier for the server associated with the entryand (ii) one or more capabilities (e.g., application services) of suchserver.

For example, a first entry 602 indicates an IP address, e.g., IPaddress₁, associated with a first server available to the client. Thefirst entry 602 further indicates the capabilities of such first server,e.g., real time communication. A third entry 606 indicates an IPaddress, e.g., IP address₃, associated with a third server available tothe client and further indicates the capabilities of such third server,e.g., real time communication and storage. A ninth entry 618 indicatesan IP address, e.g., IP address₉, associated with a ninth serveravailable to the client and further indicates the capabilities of suchninth server, e.g., storage. In some embodiments, each IP address maycomprise a 32 bit IP address.

In some embodiments, a client may receive and/or generate a separatelist for each type of server capability (e.g., application service).

FIG. 7 is a graphical representation of a list (shown in the form of atable 700) of the servers 12 that are available to the client and havethe capability of real time communication.

FIG. 8 is a graphical representation of a list (shown in the form of atable 800) of the servers 12 that are available to the client and havethe capability of storage.

FIG. 2 is a diagram illustrating subsystems of a server failover andload balancing engine, e.g., one of server failover and load balancingengines 16 a-16 c, in accordance with some embodiments.

Referring to FIG. 2, in accordance with some embodiments, each serverfailover and load balancing engine, e.g. server failover and loadbalancing engines 16 a-16 c, may include a CAI subsystem 30 and aservice mapping subsystem 32.

The CAI subsystem 30 facilitates failover, scaling, and/or locality ofthe client information. The CAI subsystem 30 associates a clientapplication identifier (CAI) with a particular application of aparticular client or group of particular clients. For example, the CAIsubsystem 30 can include a real time communication session between twoor more clients, use of read/write storage by one or more clients,streaming audio/video content from one client to a group of clients,application servicing a group of clients (e.g., payroll), etc. The CAIsubsystem 30 defines a partition of the server system used to service aparticular set of clients. This limits data and communication to thesubset of the entire system, and enables scaling. The redundancyrequirements are defined for each particular case within the partition(e.g., subset). If state (e.g., data) retention is involved, then theredundancy factor (e.g., two or greater) determines the replicationwithin the subset, and subset size. If there is only a real-timecomponent (e.g., for real time communication or live video streaming),the entire system can be involved so the redundancy factor is equal tothe number of servers in the entire system. In all these cases, two ormore clients that have agreed on the same CAI will always select thesame server or the same subset of servers. One possible embodiment ofthe CAI is a large number (e.g., 128, 512, or more bits), kept secretfrom outsiders. It can be self-assigned (e.g., by insiders by a randomchoice), which can practically eliminate all collisions due to the largequantity of available possible numbers. Other embodiments are alsoenvisioned (e.g., centralized or semi-centralized assignments). Itshould be understood by those of ordinary skill in the art that anysuitable assignment system, method or protocol may be used.

The service mapping subsystem 32 maps each CAI to a particular server ora server subset for proper functioning of the system. Two or moreclients that have agreed on the same CAI will always select the sameserver or the same subset of servers. This mapping works in the absenceof a real-time directory service. Other than a recent directory map ofthe system, no other external information is required. One possiblemapping method that could be used with the system is Highest RandomWeight (HRW). See, e.g.,https://en.wikipedia.org/wiki/Rendezvous_hashing, the entirety of whichis incorporated herein by reference.

FIG. 3 is a diagram showing one of the one or more clients 22communicating with one of the plurality of servers 12 using a list ofserver IP addresses 136, in accordance with some embodiments.

Referring to FIG. 3, in accordance with some embodiments, the system 10may generate and/or otherwise provide a directory list of servers thatare available to the client (with server identities represented by IPaddresses). The server failover and load balancing engine in the client22 may combine the CAI with IP addresses of servers are available to theclient and provide the desired application (e.g., real timecommunication and/or other function) and may perform the HRW method onthis list of combinations, to generate a CAI-specific sorted list ofservers 136 that provide the desired application (e.g., real timecommunication and/or other function). In other words, the engine maysort the list by HRW (CAI, IP).

The client 22 may select a server (e.g., server 12 a) from theCAI-specific sorted list of servers 136 by starting at the top of thelist, and if the server at the top of the list is unavailable, the nextN−1 servers 12 b-12 n may be tried in succession, where N is theredundancy factor. Eventually, the client 134 selects an availableserver (e.g., server 12 d) and establishes connection with that server(e.g., server 12 d).

For example, if two clients wish to establish a communication linkbetween them, mediated by a “communication application,” the clientsagree on a CAI, and run the above-described HRW algorithm. Because thedirectory map of both clients is identical, each of the clients willcome up with the same sorted list, and will pick the same working serverfrom that list. As there is no state in this case, all servers providingthis “communication application” can be on the list, providing highredundancy.

FIG. 9 is a graphical representation of a list (or other definition)prior to sorting after hashing, in accordance with some embodiments.

Referring to FIG. 9, the list (or other definition) is shown in the formof a table 900 having a plurality of entries, e.g., entries 902-916. Inthe illustrated embodiment, each entry is associated with a particularone of the plurality of servers 12 and indicates: (i) the IP address orother identifier for the server associated with the entry, a combinationof the CAI and the IP address of the server (e.g., concatenation of IPaddress and CAI) and (iii) a hash out value that results from hashingthe combination of the CAI and the IP address of the server.

For example, a first entry 902 indicates an IP address, e.g., IPaddress₁, associated with a first server, a combination (e.g., IPaddress₁ & CAI)) of such IP address and the CAI, and a hash out value,e.g., hash out₁, that results from hashing the combination. In someembodiments, each IP address comprises 32 bit IP address, the CAIcomprises 128 bits and the combination of the IP address and the CAIcomprises 160 bits. In some embodiments, the agreed on CAI comprises a128 bit identifier representing a telephone number.

FIG. 10 is a graphical representation of the list (or other definition)of IP addresses shown in table 900 after sorting based on the hash outvalues in the table 900, in accordance with some embodiments.

Referring to FIG. 10, the sorted list (or other definition) is shown inthe form of a table 1000 having a plurality of entries, e.g., 1002-1016.For purposes of illustration, it has been assumed that the hash outvalues in the table 900 define the following descending sequence of hashout values (greatest to smallest): hash out₇, hash out₃, hash out₁, hashout₂, hash out₆, hash out₅, hash out₄, hash out₈.

As stated above, the sorted list is not limited to the forms describedabove. In accordance with some embodiments, the sorted list may compriseany type(s) of information, in any form(s), that defines an order inwhich to attempt to contact servers until at least one functioning oneof the servers is contacted.

The above communication examples is just one non-limiting example, andmany other applications are possible as should be understood by those ofordinary skill in the art.

In another example, a group of clients belonging to the same businesswants to access payroll. They all agree on a CAI, and select afunctioning server, which has access to payroll data related to thisgroup (e.g., defined by CAI). The application services in this case havestate (e.g., payroll information), and a redundancy requirement withfactor N, usually greater than 1. To achieve this, in some embodiments,each payroll application service (and/or other portion of thefunctioning server), when it receives a request/session from aparticular client, also receives CAI, and calculates (or otherwisegenerates) the HRW sorted list itself. Then it finds the first N serverson the list (e.g., one of them is itself), and replicates all payrollinformation for this CAI to the other N−1 servers on the list. In someembodiments, the functioning server receives the HRW sorted list (or aportion thereof) from the requesting client and does not generate theHRW sorted list itself. In some embodiments, the functioning server doesnot replicate the information to the other N−1 servers on the list. Inthe latter embodiments, the requesting client may replicate theinformation to the other N−1 servers.

FIG. 11 is a graphical representation of a list (or other definition)prior to sorting after hashing, in accordance with some embodiments.

Referring to FIG. 11, the list (or other definition) is shown in theform of a table 1100 having a plurality of entries, e.g., entries1102-1116. In the illustrated embodiment, each entry is associated witha particular one of the plurality of servers 12 and indicates: (i) theIP address or other identifier for the server associated with the entry,a combination of the CAI and the IP address of the server (e.g.,concatenation of IP address and CAI) and (iii) a hash out value thatresults from hashing the combination of the CAI and the IP address ofthe server.

For example, a first entry 1102 indicates an IP address, e.g., IPaddress₃, associated with a third server, a combination (e.g., IPaddress₃ & CAI)) of such IP address and the CAI, and a hash out value,e.g., hash out₃, that results from hashing the combination. In someembodiments, each IP address comprises 32 bit IP address, the CAIcomprises 104 bits and the combination of the IP address and the CAIcomprises 136 bits.

FIG. 12 is a graphical representation of the list (or other definition)of IP addresses shown in table 1100 after sorting based on the hash outvalues in the table 1100, in accordance with some embodiments.

Referring to FIG. 12, the sorted list (or other definition) is shown inthe form of a table 1200 having a plurality of entries, e.g., 1202-1216.For purposes of illustration, it has been assumed that the hash outvalues in the table 1100 define the following descending sequence ofhash out values (greatest to smallest): hash out₇, hash out₃, hash out₉,hash out₁₀, hash out₆, hash out₅, hash out₄, hash out₈.

In some embodiments, the client sends the selected server information toidentify a record (of any size) within the selected server at which tostore the data (if the data is being stored) and/or from which toretrieve the data (if the data is being retrieved), In some embodiments,the information comprises 128 bits. In some embodiments, the informationmay comprise the CAI, which the selected server may use as a key toidentifies a partition within the selected server, and a record numberthat identifies a record within the identified partition. In someembodiments, the CAI used to identify the partition may comprise 104bits and the record number used to identify the record within thestorage partition may comprise 24 bits.

As stated above, the sorted list is not limited to the forms describedabove. In accordance with some embodiments, the sorted list may compriseany type(s) of information, in any form(s), that defines an order inwhich to attempt to contact servers until at least one functioning oneof the servers is contacted.

The above storage example is just one more non-limiting example, andmany other applications are possible as should be understood by those ofordinary skill in the art.

FIG. 4 is a flowchart of the process 150, in accordance with someembodiments. In step 152, the system 10 electronically (or otherwise)generates a directory list with server identities represented by IPaddresses. In step 154, the system electronically (or otherwise)generates an application specific directory list using a clientapplication identifier to identify servers with a desired application.In step 156, the client electronically (or otherwise) applies the HRWmethod on the application specific directory list to electronically (orotherwise) generate a CAI-specific sorted list of servers that providethe desired application. In step 158, one or more clients attempt tocontact the first server listed in the CAI-specific sorted list ofservers. In step 160, a determination is made as to whether an answerwas received from the server selected. If not, then in step 162, theclient attempts to contact the next server listed in the CAI-specificsorted list of servers. If so, then in step 164, an electrical or datacommunication is established between the one or more clients and theserver selected.

FIG. 13 is a flow chart of a process 1300, in accordance with someembodiments.

In accordance with some embodiments, the method may be used in serverfailover and/or load balancing.

The method 1300 is not limited to the order shown in the flow chart.Rather, embodiments of the method 1300 may be performed in any orderthat is practicable. For that matter, unless stated otherwise, anymethod disclosed herein may be performed in any order that ispracticable.

Unless stated otherwise, the method 1300 (and/or any other methoddisclosed herein) may be performed by in any manner. In someembodiments, the method, (and/or any other method disclosed herein) orone or more portions thereof, may be performed by one or more portionsof the system 10 and/or any other processing system.

In some embodiments, a non-transitory computer readable medium may haveinstructions stored thereon, which if executed by a machine result inperformance of the method 1300 (and/or any other method disclosedherein) or one or more portions thereof.

Referring to FIG. 13, in accordance with some embodiments, at 1302, themethod may include executing, by one or more clients, an engine toselect a target server or server subset among a plurality of servers,using a client application identifier.

In some embodiments, two or more clients, using the same clientapplication identifier, select the same target server or server subset.

In some embodiments, the engine includes a service mapping subsystemconfigured to map each client application identifier to the targetserver or server subset.

In some embodiments, the service mapping subsystem is configured to mapsaid client application identifier using Highest Random Weight.

In some embodiments, the client application identifier comprises a largenumber.

In some embodiments, executing an engine to select a target server orserver subset among a plurality of servers, using a client applicationidentifier comprises: executing, by a first one of the one or moreclients, an engine to select a target server or server subset among aplurality of servers, using a client application identifier; andexecuting, by a second one of the one or more clients, the engine toselect the target server or server subset among the plurality ofservers, using the client application identifier.

In some embodiments, executing an engine to select a target server orserver subset among a plurality of servers, using a client applicationidentifier comprises: receiving, by an engine executed by a client,information indicative of identifies of servers that provide a desiredapplication; and generating, by the engine executed by the client, basedat least in part on the information and a client application identifier,a client application identifier specific sorted list of servers thatprovide the desired application.

In some embodiments, the sorted list may comprise any type(s) ofinformation, in any form(s), that defines an order in which to attemptto contact servers until at least one functioning one of the servers iscontacted.

In some embodiments, the large number comprises at least 128 bits. Insome embodiments, the large number comprises at least 512 bits.

FIG. 5 is a diagram showing an architecture 200, in accordance with someembodiments. In some embodiments, one or more of the systems and/ordevices (and/or portion(s) thereof) disclosed herein may have anarchitecture that is the same as and/or similar to one or more portionsof the architecture 200. In some embodiments, one or more of theplurality of servers 12 in the server failover and load balancing system10 and/or one or more of the one or more clients 22 in the serverfailover and load balancing system 10 have an architecture that is thesame as and/or similar to one or more portions of the architecture 200.

In some embodiments, one or more of the methods (or portion(s) thereof)disclosed herein may be performed by a system, apparatus and/or devicehaving an architecture that is the same as or similar to thearchitecture 200 (or portion(s) thereof).

The architecture may be implemented as a distributed architecture or anon-distributed architecture. A distributed architecture may be acompletely distributed architecture or a partly distributed-partly nondistributed architecture.

Referring to FIG. 5, in accordance with some embodiments, thearchitecture 200 includes a processing system 202 that may include oneor more of a storage device 204, a network interface 208, acommunications bus 210, a central processing unit (CPU) (microprocessor)212, a random access memory (RAM) 214, and one or more input devices216, such as a keyboard, mouse, etc. The processing system 202 may alsoinclude a display (e.g., liquid crystal display (LCD), cathode ray tube(CRT), etc.). In some embodiments, the storage device 204 may compriseany suitable, computer-readable storage medium such as disk,non-volatile memory (e.g., read-only memory (ROM), erasable programmableROM (EPROM), electrically-erasable programmable ROM (EEPROM), flashmemory, field-programmable gate array (FPGA), etc.). In someembodiments, the processing system 202 may comprise a networked computersystem, a personal computer, a smart phone, a tablet computer etc. Insome embodiments, a server failover and load balancing engine 16 may beembodied as computer-readable program code stored on the storage device204 and executed by the CPU 212 using any suitable, high or low levelcomputing language, such as, for example, Python, Java, C, C++, C #,.NET, MATLAB, etc. In some embodiments, the network interface 208 mayinclude an Ethernet network interface device, a wireless networkinterface device operable with one or more suitable wireless protocol,or any other suitable device that permits the server 202 to communicatevia the network. In some embodiments, the CPU 212 may include anysuitable single or multiple-core microprocessor of any suitablearchitecture that is capable of implementing and running the serverfailover and load balancing engine 16. In some embodiments, the randomaccess memory 214 may include any suitable, high-speed, random accessmemory typical of most modern computers, such as dynamic RAM (DRAM),etc.

Unless stated otherwise, any process (sometimes referred to herein as amethod) disclosed herein is not limited to an order shown in a flowchart. Rather, embodiments may be performed in any order that ispracticable.

Unless stated otherwise, any method disclosed herein may be performed inany manner. In some embodiments, a method (or one or more portionsthereof) may be performed by one or more portions of the system 10.

In some embodiments, a non-transitory computer readable medium may haveinstructions stored thereon, which if executed by a machine result inperformance of any one or more methods (or one or more portions thereof)disclosed herein.

Unless stated otherwise, a processor may comprise any type of processor.For example, a processor may be programmable or non-programmable,general purpose or special purpose, dedicated or non-dedicated,distributed or non-distributed, shared or not shared, and/or anycombination thereof. A processor may include, but is not limited to,hardware, software, firmware, and/or any combination thereof. Hardwaremay include, but is not limited to off the shelf integrated circuits,custom integrated circuits and/or any combination thereof. In someembodiments, a processor comprises a microprocessor. Software mayinclude, but is not limited to, instructions that are storable and/orstored on a computer readable medium, such as, for example, magnetic oroptical disk, magnetic or optical tape, CD-ROM, DVD, RAM, EPROM, ROM orother semiconductor memory. A processor may employ continuous signals,periodically sampled signals, and/or any combination thereof. If aprocessor is distributed, two or more portions of the control/storagecircuitry may communicate with one another through a communication link.

Unless stated otherwise, a processing system is any type of system thatincludes at least one processor.

Unless stated otherwise, a communication link may be any type ofcommunication link, for example, but not limited to, wired (e.g.,conductors, fiber optic cables) or wireless (e.g., acoustic links,electromagnetic links or any combination thereof including, for example,but not limited to microwave links, satellite links, infrared links),and/or combinations thereof, each of which may be public or private,dedicated and/or shared (e.g., a network). A communication link may ormay not be a permanent communication link. A communication link maysupport any type of information in any form, for example, but notlimited to, analog and/or digital (e.g., a sequence of binary values,i.e. a bit string) signal(s) in serial and/or in parallel form. Theinformation may or may not be divided into blocks. If divided intoblocks, the amount of information in a block may be predetermined ordetermined dynamically, and/or may be fixed (e.g., uniform) or variable.A communication link may employ a protocol or combination of protocolsincluding, for example, but not limited to the Internet Protocol.

Unless stated otherwise, the term “receiving” means receiving in anymanner(s) from any source(s) internal and/or external.

Unless stated otherwise the term “define” means “define directly and/orindirectly”.

Unless stated otherwise, terms such as, for example, “in response to”and “based on” mean “in response at least to” and “based at least on”,respectively, so as not to preclude being responsive to and/or based on,more than one thing.

Unless stated otherwise, terms such as, for example, “coupled to”, “sendto” and “receive from” mean “coupled directly and/or indirectly to”,“send directly and/or indirectly to” and “receive directly and/orindirectly from”, respectively.

Unless stated otherwise, terms such as, for example, “comprises”, “has”,“includes”, and all forms thereof, are considered open-ended, so as notto preclude additional elements and/or features. In addition, unlessstated otherwise, terms such as, for example, “a”, “one”, “first”, areconsidered open-ended, and do not mean “only a”, “only one” and “only afirst”, respectively. Moreover, unless stated otherwise, the term“first” does not, by itself, require that there also be a “second”.

Having thus described the system and method in detail, it is to beunderstood that the foregoing description is not intended to limit thespirit or scope thereof. It will be understood by those of ordinaryskill in the pertinent art that the embodiments of the presentdisclosure described herein are merely exemplary and that a personskilled in the art, based on the teachings herein, may make any numerousvariations and modifications without departing from the spirit and/orscope of the disclosure. All such variations and modifications,including those discussed above, are intended to be included within thescope of the disclosure. By way of example only, the disclosurecontemplates, but is not limited to, embodiments having any one or moreof the features set forth in the above description in any combinationwith each other. By way of another example only, the disclosurecontemplates, but is not limited to, embodiments that do not include anyone or more of the features set forth in the above description.Accordingly, the description of embodiments herein is to be taken in anillustrative as opposed to a limiting sense, and neither the inventionnor the disclosure is limited to the particular embodiments orcombinations of features described herein.

What is claimed:
 1. A method for server load balancing comprising:receiving, at a client device, a directory list with server identitiesfor each of a plurality of servers, each server associated with a randomclient application identifier, the random client application identifierbeing associated with an application service provided by one of theplurality of servers; generating, at the client device, a sorted listfor the plurality of servers from the directory list, the sorted listbeing generated based at least in part on the random client applicationidentifier; contacting, by the client device, a selected server from thesorted list by reviewing the sorted list until an answer is receivedfrom one of the plurality of servers; and, establishing, by the clientdevice, communication with the selected server.
 2. The method of claim1, wherein the random client application identifier includes at least128 bits.
 3. The method of claim 1, wherein the random clientapplication identifier includes at least 512 bits.
 4. The method ofclaim 1, wherein the server identities include an IP address.
 5. Themethod of claim 1, wherein each of the plurality of servers areconfigured to provide a directory service.
 6. The method of claim 1,wherein the directory service is configured to provide a list of serverstagged with one or more application services each server supports. 7.The method of claim 1, wherein the application service serves only asubset of a plurality of client devices
 8. A server in communicationwith the database and connected to a network and in communication with adirectory service, the server comprising: one or more applicationservices configured to respond to an application service request from aclient; wherein the server is configured to: update a database with aclient application identifier associated with a server identity inresponse to a capability of the one or more application serviceschanging.
 9. The server of claim 8 wherein the directory service isconfigured to respond to an directory information request from at leastone of the client, the server, or an additional server.
 10. The serverof claim 9 wherein the directory information includes the serveridentity associated with the client application identifier indicatingthe capability of the one or more application services of an associatedserver.
 11. The server of claim 10 wherein the server further comprisesthe directory service.
 12. The server of claim 8 wherein the server isfurther configured to service client requests for application services.13. The server of claim 12 wherein the client request includes a requestfor an application session.
 14. The method of claim 8, wherein theserver identities includes an IP address.
 15. A system comprising: adatabase configured to store a client application identifier and anassociated server identity, the client application identifier indicatingan application service capability of an associated server; a server incommunication with the database and connected to a network, the servercomprising one or more application services and being configured to:update the database with a new client application identifier associatedwith the server identity in response to the application servicecapability of the one or more application services changing, wherein theserver is the associated server.
 16. The system of claim 15 furthercomprising a directory service configured to respond to an directoryinformation request from a client, the associated server, or anadditional server.
 17. The system of claim 16 wherein the directoryinformation includes the server identity associated with the clientapplication identifier indicating the capability of the one or moreapplication services of the associated server.
 18. The system of claim17 wherein the associated server further comprises the directoryservice.
 19. The system of claim 15 wherein the associated server isfurther configured to service client requests for application services.20. The system of claim 19 wherein the client request includes a requestfor an application session.